Blackberry and Blood Orange Cake

Chocolate sour cream cake soaked with blood orange syrup, layered with semi-sweet ganache and vanilla pastry cream embedded with fresh blackberries, surrounded by piquant blood orange whipped cream and topped with a blackberry mirroir. 

Note: this cake takes a few days... I will explain my process using three days, with the cake being served on the third day in the evening, but you could spread it out over four days, or cut it down to two.

For the chocolate sour cream cake:
1/3 cup butter, unsalted, room temperature, in small pieces
3 ounces unsweetened chocolate, chopped roughly, melted
1 1/2 cups flour
2 tsp baking soda
1 tsp baking powder
2 eggs
1 1/2 cups sugar
1/2 cup sour cream

Oven at 275 degrees.  Grease the bottom and sides of a 9x3 cake pan, line bottom with parchment.

Stir together flour, baking soda, baking powder.  Set aside.

Start some water on the stove to boil, about 1 1/2 cups.

In a stand mixer, beat eggs and sugar until it gets really thick, maybe seven or so minutes.  Add the butter, and mix until smooth.  Add sour cream and mix again until smooth.  Mix in melted warm chocolate until fully incorporated.  Add the sifted ingredients, mix but be careful not too much.

Once your water is boiling, measure out 1 cup and add to batter, mix until smooth.  It will thin out quite a bit.

Pour batter into greased/lined pan.  There might be a bit too much batter, do not overfill your pan.  Bake until springy and a toothpick comes out clean.  Mine took around 70-75 minutes.  Watch carefully, it could be less or more.

Once done, allow to cool before unmolding.  Wrap in plastic until ready to use so it doesn't dry out.

I usually make this on the first day, so two days before serving.  Can be kept at room temperature.



To make blood orange concentrate (needed for the syrup and the whipped cream):

You will need fresh blood orange juice, about 3 cups, the amount of oranges needed to get the juice varies on how large/ripe your oranges are.  Reserve one orange for decor purposes.  Pour the juice into a saucepan, heat over medium heat until reduced to 1 cup.  Strain, and cool.

I usually make this on the first day.  Refrigerate until needed.




To make blood orange syrup:
1/3 cup sugar
1/2 cup blood orange concentrate (above)
1/3 cup water

Heat sugar and water to a boil, stirring a little.  Remove from heat, cool completely.  Stir in blood orange concentrate.

This is also made on the first day.  Refrigerate until needed.



To make the semi-sweet chocolate ganache:
3 cups semi-sweet chocolate chips
1 1/2 cups heavy cream
2 tsp rum

Put chocolate chips in a bowl, set aside.  Heat cream to a boil, then pour over chocolate.  Let sit for five minutes.  Then, use a spatula to stir gently until fully combined, shiny, and smooth.

Transfer to a food processor, add rum, and process to blend.  Allow to cool at room temperature.

I make this on the first day, and refrigerate until needed.  It will warm up very quickly in the microwave (be very careful not to overheat) or let it sit at room temperature for a few hours.



For the blood orange curd (needed to make the whipped cream):
1 gelatin sheet
4 eggs
4 egg yolks
1/2 cup sugar
1/3 cup blood orange concentrate (above)
1/2 cup fresh lemon juice
2/3 cup butter, unsalted, room temperature, in small pieces

Soften gelatin in 2 cups cool water, less than 5 minutes.  Proceed to the next bit, but when it has softened squeeze it out so it is ready for quick use.

Whisk eggs, egg yolks, sugar, blood orange concentrate, and lemon juice in a double boiler.  Whisk constantly until it thickens to a custard, 5-7 minutes.  Quickly whisk in the butter and remove from heat.  Whisk in the softened gelatin sheet.

Strain into a bowl.  Cover with plastic wrap pressed right onto the surface, and refrigerate.

I make this on the first day, too.  When ready to make whipped cream, use directly from the refrigerator. 

Vanilla pastry cream - step 1:
1 1/2 cup heavy cream
1 cup milk
1/2 vanilla bean, scraped
1/2 cup sugar
6 egg yolks
2 tbsp cornstarch
2 tbsp potato starch
1 tbsp  unsalted butter, room temperature

Heat cream, milk, and vanilla bean seeds to a boil.

While it is heating, whisk together sugar, egg yolks, and both starches.  When cream mixture has begun to boil, slowly pour it into egg yolk mixture while whisking constantly.  Pour all back into the saucepan, and cook, medium heat, whisking constantly, until it has thickened into a custard.   Strain into a bowl, and mix in the butter.

Cover with plastic wrap pressed onto surface, and cool in refrigerator.

This is made on day 1 also, use directly from refrigerator when ready.




Vanilla pastry cream - step 2:
1 1/4 cup heavy cream
4 gelatin sheets
1/3 cup unsalted butter, room temperature, small pieces
Vanilla Pastry Cream - step 1 (above)

Whip cream until medium-soft peaks form, hold in refrigerator.

Soften gelatin sheets in cool water for five minutes, squeeze out water, and melt gently in a small saucepan.

Place vanilla pastry cream step 1 in the bowl of a stand mixer, beat gently to loosen.  Add butter, mix until combined.  While machine is beating fast, pour in the melted gelatin in a slow stream.   Mix until smooth.  Take whipped cream out of refrigerator, and fold into pastry cream with a rubber spatula.

This step is for day 2, which is the day we will be assembling the cake, do not make this step any day but assembly day.




Blood orange whipped cream:
4 cups heavy cream
1/2 cup minus 1 tbsp sugar
blood orange curd (above)

Whip cream and sugar until stiff peaks.  Using a rubber spatula, fold in blood orange curd (it helps to loosen curd with a whisk before folding in) until well mixed and an even color throughout.  Do not over mix, it will make it weak.

This step is for day 2, which is the day we will be assembling the cake, do not make this step any day but assembly day.




Assembly:
1 9" chocolate sour cream cake
1 recipe blood orange syrup
1 recipe semi-sweet chocolate ganache
1 recipe blood orange whipped cream
1 recipe pastry cream
2 pints fresh blackberries, reserve the prettiest and largest for decor

You will also need a 10x4 or 10x5 removable bottom cake pan, 10x3 could work but your room to build upwards is limited with it.  In a pinch, springform will work, but not nearly as well.  Also, a pastry bag fitted with a 1/4" or 1/2" tip (plain is good, but a star or whatever will work ok), this is not entirely necessary but makes things easier.

Place a ten inch cardboard cake round into the cake pan instead of the metal bottom.

Take your cooled cake, and using a long thin serrated knife level out the top.  Cut the leveled cake into three even layers.

Set aside 1 1/2 cups blood orange whipped cream.  Fill your pastry bag with the rest.

Place the first layer onto the cardboard round in the cake pan.  Center it nicely.  Drizzle or brush with a little less than 1/3 of the blood orange syrup.  Pipe the blood orange whipped  cream into the space between the edge of the cake and the pan. ((You will do this all the way up, therefore creating a smooth whipped cream outside to your cake.)) Spread about 1/3 of the ganache over the soaked cake layer, being careful not to get in into the outer layer of whipped cream.  On top of the ganache, spread a thick layer of pastry cream, but not more than 1/2 of the recipe.  Press the blackberries into the pastry cream in one layer, cut them in half if you'd like.  Now, again, pipe the whipped cream into the space on the side, making sure to fill it completely and not let any of the inside layers seep through.

Now place your second layer of cake in the pan, centering it well.  Soak with another 1/3 or less of the syrup.  Pipe whipped cream around the outer rim.  Spread with another 1/3 ganache, top with another thick layer pastry cream and more blackberries.

Now for the last layer of cake.  Center it in there.  Soak with syrup.  Pipe whipped cream around edge. Spread on ganache.  Pipe a little more around the edges. Now, we are going to use that 1 1/2 cups whipped cream we set aside to cover the top.  Being careful not to push ganache into the outer rim, spread whipped cream over the top of the cake, making a very smooth even top.

Tightly wrap in plastic wrap and place in the freezer overnight.

This assembly is done on the second day, the day before serving.  Since for my example, I am serving the cake in the evening, I will do tomorrow's steps in the morning so that the cake will have time to defrost for eight hours.  Be sure to think about defrost time, no one wants a frozen cake! (unless it's ice cream cake!)

Blackberry Miroir
8 ounce frozen blackberries
3 gelatin sheets
1/3 cup sugar
3 tbsp glucose (may use light corn syrup if glucose is unavailable)
1/3 cup blackberry jam, strained (raspberry jam will work too, and result in a lighter color miroir)

Process the 1 cup frozen blackberries in a food processor until pureed.  Measure out 1/2 cup.

Soften gelatin in cool water, 5 minutes.

Heat puree, sugar, glucose, and jam in a saucepan, medium-high heat, bring to a boil.  Using a candy thermometer, heat until 220 degrees. Removes from heat.

Squeeze excess water form gelatin, and stir into berry mixture.  Heat again, about 2 minutes, over medium-high heat.

Strain, and let cool slightly.  Must be used while warm and liquid though.

Made on the third day in the morning, at least 10 hours before serving.


Finishing:
1 blackberry, large and pretty
1 blood orange, sliced into thin even slices
1 assembled cake, straight from the freezer
1 recipe blackberry miroir, still quite warm

Remove cake from freezer, and pour the warm blackberry miroir on the top of the cake.  Quickly swirl it around so the miroir reaches the sides of the pan and forms and even glassy top.

Return to freezer for an hour or so.

Now to unmold the cake, gently heat the sides with a hairdryer (a towel, soaked with hot water and rung out, pressed to the sides also works).  Don't get it too warm, just ever so slightly so it can slide out.   Once it can slide out, simply push the cardboard cake round up from the bottom so the cake slides out of the sides of the pan.  Viola!

If the whipped cream on the sides of your cake isn't completely smooth, you can smooth it out with an offset spatula, but it shouldn't need that.

Decorate as you wish with the orange slices and blackberry.  If your oranges are particularly juicy, or you're just worried about the miroir getting too mushy, either dry them out a bit on paper towels. or wait until it is time to display the cake to decorate it.  I arranged my slices in a spiral, and placed the blackberry in the middle, simple but elegant.  A toothpick works well to help the blackberry stand up.

Defrost cake for at least 8 hours in the refrigerator, and at least 1 hour right before serving at room temperature.  You can keep it in the refrigerator for up to 16 hours, and at room temperature for up to 3 hours.

Finishing with the miroir must be done on the third, and final, day.  At least 9 hours before serving to give it plenty of time to defrost.  Other decorating can be done whenever.

Your cake is now ready to serve!  Remember to enjoy it after all that hard work!